Escape sequences such as encodings of terminal commands and function keys

learn more… | top users | synonyms

35
votes
5answers
39k views

How to clear terminal completely?

When we use clear command or Ctrl+L in terminal, it clears terminal but we can still scroll back to view the last used commands. Is there a way to completely clear the terminal?
32
votes
6answers
21k views

Removing control chars (including console codes / colours) from script output

I can use the "script" command to record an interactive session at the command line. However, this includes all control characters and colour codes. I can remove control characters (like backspace) ...
23
votes
4answers
37k views

How to escape quotes in shell?

I'm having trouble with escaping characters in bash. I'd like to escape single and double quotes while running a command under a different user. For the purposes of this question let's say I want to ...
22
votes
2answers
3k views

Where do my ANSI escape codes go when I pipe to another process? Can I keep them?

I sometime want to pipe the color-coded output fror a process, eg. grep... but when I pipe it to another process, eg. sed, the color codes are lost... Is the some way to keep thes codes intact ? ...
20
votes
5answers
6k views

Is there any reason why I get ^[[A when I press up arrow at the console login screen?

Whenever I'm at the console login, I press up arrow intentionally to see the previously typed commands. But I see this ^[[A. But when I press Ctrl Alt Print Screen Scroll Lock Pause Break Page Up ...
19
votes
2answers
32k views

Why does Ctrl-D (EOF) exit the shell?

Are you literally "ending a file" by inputting this escape sequence, i.e. is the interactive shell session is seen as a real file stream by the shell, like any other file stream? If so, which file? ...
19
votes
2answers
3k views

How to avoid escape sequence attacks in terminals?

Reading the details of CVE-2009-4487 (which is about the danger of escape sequences in log files) I am a bit surprised. To quote CVE-2009-4487: nginx 0.7.64 writes data to a log file without ...
19
votes
3answers
786 views

How to prevent random console output from breaking the terminal?

There are many questions on SE that show how to recover from terminal broken by cat /dev/urandom. For those that are unfamiliar with this issue - here what it is about: You execute cat /dev/urandom ...
16
votes
3answers
9k views

Where do I find a list of terminal key codes to remap shortcuts in bash?

For example: "\e[1;5C" "\e[Z" "\e-1\C-i" I only know bits and pieces, like \e stands for escape and C- for Ctrl, but what are these numbers (1) and letters (Z)? What are the ;, [ and - signs for? ...
15
votes
4answers
21k views

How to make the terminal display user@machine in bold letters?

I have seen in some screen-shots (can't remember where on the web) that the terminal can display the [username@machine /]$ in bold letters. I'm looking forward to getting this too because I always ...
15
votes
2answers
569 views

How do I use grep while keeping the original text color? [duplicate]

For example, I have a output: Hello, this is the output. (let's say that for example hello is colored red, and the is colored green, and output is colored purple). Now, let's say that this is the ...
14
votes
4answers
1k views

Escape sequences in output of script called from ncurses application

I'm currently running mcabber as my Jabber client (which uses ncurses) in a tmux session on my homeserver. Locally i run iTerm2 as a terminal emulator, which supports the triggering of growl ...
10
votes
1answer
1k views

Caret square bracket square bracket A ^[[A - What does it mean?

Apologies if this has already been asked, but I have no idea how I can find this out myself - when I search for "^[[A" in any search engine it ignores the "^[[" part altogether. Anyway, my question: ...
9
votes
3answers
26k views

Escape sequences with “echo -e” in different shells

I just noticed that it seems like the flag -e does not exist for the echo command in my shell on Linux. Is this just a messed up setting or is it "normal"? Some code as an example: #!/bin/sh echo -e ...
9
votes
2answers
3k views

How do I background an SSH session? [duplicate]

Possible Duplicate: How can I break away from an SSH session that has crashed? I have started an SSH session on the command line, but now I want to get back to my local command line. For any ...
9
votes
2answers
2k views

The difference between \e and ^[

Gilles wrote: character 27 = 033 = 0x1b = ^[ = \e Demizey wrote: ^[ is just a representation of ESCAPE and \e is interpreted as an actual ESCAPE character Then I also found this line from ...
8
votes
6answers
9k views

How can I create a file with multiple lines from the command-line? [duplicate]

How can I enter the following contents in a file: Hi abcd I tried using echo "Hi\nabcd" >> ab.txt, but in the file it's written as is (the \n is included, instead of a newline)
8
votes
3answers
2k views

Make Less highlight search patterns instead of italicizing them

To my understanding man uses less as a pager, and when searching for keywords using less it "highlights" keywords with italics. I find that really inconvenient, so I'd like to change this to something ...
8
votes
2answers
779 views

How to determine the current color of the console output?

I know that, if a coloured terminal is available, one can colour the output of it using escape characters. But is there a possibility to find out, which colour the output is currently being displayed ...
7
votes
4answers
400 views

is there a pastebin service that supports terminal escape sequences?

Is there a pastebin service that supports colors? I understand some of them have syntax hilighting, but I'd like to do arbitrary coloring, preferably using the terminal escape sequences. Example, i'd ...
7
votes
2answers
9k views

export HTTP_PROXY and special characters in passwd

Suppose for the sake of argument my password below is abc123@ I need to authenticate my linux machine through a corporate proxy to get patches and updates... normally I'd use this: export HTTP_PROXY=...
7
votes
2answers
625 views

DEC ANSI command sequence questions; cursor movement

So I'm writing a terminal emulation (I know, I should just compile putty, etc.) and am at the stage of plodding through vttest to make sure it's right. I'm basing it on the VT102 for now but will add ...
6
votes
2answers
449 views

What is the gnome-terminal ANSI escape sequence for “CTRL + arrow/s”?

I am trying to configure my bash ~/.inputrc to these settings (Note: ←, → mean the left and right arrow keys) Ctrl + ← - should jump back a word Ctrl + → - should jump forward a word Currently I ...
6
votes
1answer
5k views

Why do I have to escape a “dot” twice?

I know that we can escape a special character like *(){}$ with \ so as to be considered literals. For example \* or \$ But in case of . I have to do it twice, like \\. otherwise it is considered ...
6
votes
1answer
275 views

How to use less in a script without getting ESC escape characters?

When I use less at the command line the output is like but when I use less from within a bash script I get: How can I use less in a bash script and not get all the escape characters and have it ...
6
votes
1answer
145 views

ANSI code translator

Is there any tool that translates text with ANSI code to text-like output? tput cap names or the like? Reason for the inquiry is that I would like to use script or the like and view the resulting ...
5
votes
5answers
1k views

What are the special characters to print from a script to move the cursor?

I found that by printing \r from a script the cursor moves to the beginning of the line. What character will move the cursor up one line? Where is a list of these special characters? EDIT: Working ...
5
votes
2answers
3k views

Passing a bash command-line argument containing a dot

How can a command-line argument containing a dot (.) be passed? Are there any escape sequences for capturing characters like dot? The following invocation of a bash-script from the shell does not ...
5
votes
2answers
11k views

Trouble in script with spaces in filename

I've got a script that scp's a file from remote host back to local. Sometimes the file names contain spaces. scp does not like spaces in its file names. For some reason my attempts at handling the ...
5
votes
2answers
5k views

Change colors in console/virtual terminal

Is there a way to alter all the available colors in console / virtual terminal? By console, I mean what you get after pressing CTRL + ALT + F1 and not anything like xterm or urxvt. So, I guess that ...
5
votes
1answer
3k views

In Bash, why is PROMPT_COMMAND set to something invisible?

On RHEL6 and CentOS 6, /etc/bashrc sets PROMPT_COMMAND here: case $TERM in xterm*) if [ -e /etc/sysconfig/bash-prompt-xterm ]; then PROMPT_COMMAND=/etc/sysconfig/bash-prompt-xterm ...
5
votes
1answer
3k views

How can I match the page break character in a regular expression?

Nano calls it ^L, but of course, typing something like $ grep -v "^\^L" file doesn't work. Its unicode codepoint is 000C. How can I match it in a regular expression?
5
votes
2answers
225 views

Background color whitespace when end of the terminal reached

I am working with control sequences for text formatting and have stumbled upon some unexpected behavior. I have some text to output, in the middle of this text there is some smaller text block ...
5
votes
1answer
457 views

How do I store colored text in a variable and print it with color later?

If I do git status --short, git lists files that are not tracked with two red question marks in front: I'm trying to store this in a variable and print it with color later. Here's my bash script: #...
5
votes
3answers
90 views

Is there any objective benefit to escape sequences over tput?

In people's '.*rc' files I see online or in various code, I tend to see a lot of people who manually use ANSI escape sequences instead of using tput. I had the understanding that tput is more ...
5
votes
1answer
3k views

Escaping of meta characters in basic/extended posix regex strings in grep

Is it possible to escape all meta characters of a string inside a variable before passing it to grep? I know similar question has been asked before on SE (here) and also a good explanation here, but I ...
5
votes
2answers
154 views

Issue with column command and color escape codes

I'm colorizing the header of a table formatted with column -ts $'\t' Works well without color codes, but when I add color codes to the first line column doesn't properly align the output. Without ...
5
votes
2answers
373 views

Escape code 50 in xterm

My coworker has the following in the ~/.bash_profile of many of our servers: echo -e "\033]50;SetProfile=Production\a" The text doesn't seem to matter, since this also works: echo -e "\033]50;...
5
votes
2answers
1k views

is it possible to send a control sequence to a terminal emulator using the keyboard

If you type echo -e '\eZ' and hit return in a shell running in an xterm, you'll see that the terminal emulator prints an obscure code 1;2c. This seems to indicate that xterm interprets the VT100 ...
5
votes
1answer
73 views

cssh intercepts F10

I am using cssh (cluster-ssh) to ssh to multiple machines simultaneously. Everything works great, except that cssh intercepts F10 key (which in cssh opens menu. This is very unfortunate, because I ...
5
votes
1answer
341 views

Escaping strings in associative arrays (bash)

I am writing a script which executes a number of programs with arguments. To simplify it as much as possible, consider the following example: programs=( "ls" "echo" ) declare -A parameters parameters[...
4
votes
2answers
471 views

Is it possible to use ANSI color escape codes in Bash here-documents?

I'm printing a message in a Bash script, and I want to colourise a portion of it; for example, #!/bin/bash normal='\e[0m' yellow='\e[33m' cat <<- EOF ${yellow}Warning:${normal} This script ...
4
votes
3answers
4k views

How to escape single quotes correctly creating an alias [duplicate]

I've been given this one-liner to know how much memory my processes consume. $ ps -u $USER -o pid,rss,command | \ awk '{print $0}{sum+=$2} END {print "Total", sum/1024, "MB"}' Now I'd like to ...
4
votes
5answers
1k views

How to use ' in alias?

I have one-line that I want to call using alias. while printf '%s ' "$(df -P / | awk 'NR==2 { print $(NF-1) }')"; do sleep 30; done I tried to escape ' like \' but it didn't work. What is the ...
4
votes
1answer
381 views

Match pattern \\\" using grep

I have a json string inside json. This got encoded multiple times and I ended up with many escape backlashes: \\\". The much shortened string looks like, '[{"testId" : "12345", "message": "\\\"the ...
4
votes
4answers
1k views

Null and escape characters

I know that a filename in Linux has no restriction whatsoever except for two characters '/' and '\0'. I know that '/' is prohibited because it is a directory separator but is there any other reason ? ...
4
votes
3answers
562 views

How to print control characters with escape sequences?

I have defined the color red using tput red=$(tput setaf 1) to colorize warnings in my program. This works fine: printf '%sfail\n' "$red" # prints 'fail' in red But on one occasion I would like ...
4
votes
2answers
6k views

How to escape < or > in a parameter in shell?

I'd like to use grep with a PCRE expression that contains the < character. Bash thinks I want to redirect, but I don't want to. How can I escape <?
4
votes
1answer
847 views

How to find out the escape sequence my keyboards sends to terminal?

Let's say we have a generic keyboard with some unknown keys which may send escape sequences to terminal. The keyboard is connected to an xterm terminal emulator running on a generic BSD/Linux. To ...
4
votes
3answers
4k views

What is the problem with the output of plink?

On my Windows7 machine, I'm traversing to the installed path of PuTTy Application and running: plink <hostname> to connect to my remote Linux host. I see some unrecognized characters in the ...